That makes no sense The search plugin has nothing to do with themes or skins. Do you have any errors in your logs after you disable the plugin and restart the forum? What about when you run ./nodebb build and restart is everything working after that?
those are the bootswatch-themes applied over the theme.
but since bootswatch-themes mainly overwrite bootstrap-variables it gets overwritten again by any theme other than vanilla.
I don't think this order is intended since I'd apply the bootswatch-variables after the theme-styles therefor it's in the admins control. But maybe the devs thought that the theme-developers shouldn't overwrite skin-able variables...
hide "revert skin" from themes-list when no skin is applied
theme-change (to vanilla) after selecting skin doesn't persist skin
no indicator which skin is selected
as of runtime less-compilation the alert to restart NodeBB after skin-selection isn't necessary, is it?